Artificial tooth enamel made of thin, flexible hydroxyapatite sheets

Japanese researchers have developed a thin, flexible artificial tooth enamel made of hydroxyapatite. Credit: Hontsu; Kinki University.

We’ve covered advances in thin, flexible ceramic aerogels and foils before, but to a certain extent, they have seemed like cool materials looking for the right application. Such is not the case for a recent news item out of Kinki University in Japan, and anyone who has endured the pleasures of dental work is likely to welcome this development.

According to a story on the university’s website, university professor Shigeki Hontsu and coinvestigator, Kazushi Yoshikawa, associate professor at Osaka Dental University, have developed the world’s first flexible hydroxyapatite material in sheet form. A story on medicalxpress.com says the sheets are only about 0.004 millimeters, which is thin enough to make them flexible. The HA composition is close enough to the real thing that it acts as an artificial dental enamel. Envisioned applications for the material include repairing damaged tooth enamel or building up thin areas that cause sensitive teeth. The films are transparent, but can be made white for cosmetic purposes, too.

They make the films by an interesting mix of brute force and straightforward methods. Under vacuum, tiny HA particles are spalled out of larger chunks by hitting the chunks with a laser beam. The dislodged particles fall onto a heated salt platform, where they crystallize. The salt platform is dissolved in water and the film is “scooped up” onto filter paper and dried. The dried film is sturdy enough to be handled, and apparently, is fairly porous. The medicalxpress story says that the film has “minute holes that allow liquid and air to escape from underneath to prevent their forming bubbles” when it is applied to the tooth.

Tests are underway with extracted human teeth, and animal tests are expected to begin soon. Hontsu and Yoshikawa have patented the technology in Japan and South Korea and are applying for patents in the US, Europe and China.

Hontsu says in the story that it will be about five years before the film is approved for use as a dental treatment and perhaps three years before it will be available for cosmetic treatments. That will leave you plenty of time to plan for a day off—it takes almost an entire day for the film to adhere fully to the tooth surface, according to Hontsu.